Internet Assigned Numbers Authority

Service Name and Transport Protocol Port Number Registry

Last Updated
2025-07-22
Expert(s)
TCP/UDP: Joe Touch; Eliot Lear, Kumiko Ono, Wes Eddy, Brian Trammell, 
Jana Iyengar, and Michael Scharf
SCTP: Michael Tuexen
DCCP: Eddie Kohler and Yoshifumi Nishida
Reference
[RFC6335]
Note
Service names and port numbers are used to distinguish between different
services that run over transport protocols such as TCP, UDP, DCCP, and
SCTP.

Service names are assigned on a first-come, first-served process, as
documented in [RFC6335].

Port numbers are assigned in various ways, based on three ranges: System
Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private
Ports (49152-65535); the different uses of these ranges are described in
[RFC6335]. According to Section 8.1.2 of [RFC6335], System Ports are 
assigned by the "IETF Review" or "IESG Approval" procedures described in 
[RFC8126]. User Ports are assigned by IANA using the "IETF Review" process, 
the "IESG Approval" process, or the "Expert Review" process, as per 
[RFC6335]. Dynamic Ports are not assigned.

The registration procedures for service names and port numbers are
described in [RFC6335].

Assigned ports both System and User ports SHOULD NOT be used without
or prior to IANA registration.

************************************************************************
* PLEASE NOTE THE FOLLOWING:                                           *
*                                                                      *
* ASSIGNMENT OF A PORT NUMBER DOES NOT IN ANY WAY IMPLY AN             *
* ENDORSEMENT OF AN APPLICATION OR PRODUCT, AND THE FACT THAT NETWORK  *
* TRAFFIC IS FLOWING TO OR FROM A REGISTERED PORT DOES NOT MEAN THAT   *
* IT IS "GOOD" TRAFFIC, NOR THAT IT NECESSARILY CORRESPONDS TO THE     *
* ASSIGNED SERVICE. FIREWALL AND SYSTEM ADMINISTRATORS SHOULD          *
* CHOOSE HOW TO CONFIGURE THEIR SYSTEMS BASED ON THEIR KNOWLEDGE OF    *
* THE TRAFFIC IN QUESTION, NOT WHETHER THERE IS A PORT NUMBER          *
* REGISTERED OR NOT.                                                   *
************************************************************************

Request an Assignment
  [https://www.iana.org/protocols/apply]

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Service Name Port Number Transport Protocol Description Assignee Contact Registration Date Modification Date Reference Service Code Unauthorized Use Reported Assignment Notes
echo 7 tcp Echo [Jon_Postel] [Jon_Postel]
echo 7 udp Echo [Jon_Postel] [Jon_Postel]
daytime 13 tcp Daytime [Jon_Postel] [Jon_Postel] [RFC867]
daytime 13 udp Daytime [Jon_Postel] [Jon_Postel] [RFC867]
qotd 17 tcp Quote of the Day [Jon_Postel] [Jon_Postel]
qotd 17 udp Quote of the Day [Jon_Postel] [Jon_Postel]
nsw-fe 27 tcp NSW User System FE [Robert_Thomas] [Robert_Thomas]
nsw-fe 27 udp NSW User System FE [Robert_Thomas] [Robert_Thomas]
time 37 tcp Time [Jon_Postel] [Jon_Postel]
time 37 udp Time [Jon_Postel] [Jon_Postel]
47 tcp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
47 udp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
57 tcp any private terminal access [Jon_Postel] [Jon_Postel]
57 udp any private terminal access [Jon_Postel] [Jon_Postel]
61 tcp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
61 udp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
bootps 67 tcp Bootstrap Protocol Server [Bill_Croft] [Bill_Croft] [RFC951] Defined TXT keys: None
bootps 67 udp Bootstrap Protocol Server
gopher 70 tcp Gopher [Mark_McCahill] [Mark_McCahill]
gopher 70 udp Gopher [Mark_McCahill] [Mark_McCahill]
netrjs-1 71 tcp Remote Job Service
netrjs-1 71 udp Remote Job Service
netrjs-2 72 tcp Remote Job Service
netrjs-2 72 udp Remote Job Service
netrjs-3 73 tcp Remote Job Service
netrjs-3 73 udp Remote Job Service
netrjs-4 74 tcp Remote Job Service [Bob_Braden] [Bob_Braden]
netrjs-4 74 udp Remote Job Service [Bob_Braden] [Bob_Braden]
75 tcp any private dial out service [Jon_Postel] [Jon_Postel]
75 udp any private dial out service [Jon_Postel] [Jon_Postel]
deos 76 tcp Distributed External Object Store [Robert_Ullmann] [Robert_Ullmann]
deos 76 udp Distributed External Object Store [Robert_Ullmann] [Robert_Ullmann]
77 tcp any private RJE service [Jon_Postel] [Jon_Postel]
77 udp any private RJE service [Jon_Postel] [Jon_Postel]
vettcp 78 tcp vettcp [Christopher_Leong] [Christopher_Leong]
vettcp 78 udp vettcp [Christopher_Leong] [Christopher_Leong]
finger 79 tcp Finger [David_Zimmerman] [David_Zimmerman] Unauthorized use by some mail users (see [RFC4146] for details)
finger 79 udp Finger [David_Zimmerman] [David_Zimmerman] Unauthorized use by some mail users (see [RFC4146] for details)
87 tcp any private terminal link [Jon_Postel] [Jon_Postel]
87 udp any private terminal link [Jon_Postel] [Jon_Postel]
swift-rvf 97 tcp Swift Remote Virtural File Protocol [Maurice_R_Turcotte] [Maurice_R_Turcotte]
swift-rvf 97 udp Swift Remote Virtural File Protocol [Maurice_R_Turcotte] [Maurice_R_Turcotte]
rtelnet 107 tcp Remote Telnet Service [Jon_Postel] [Jon_Postel]
rtelnet 107 udp Remote Telnet Service [Jon_Postel] [Jon_Postel]
uucp-path 117 tcp UUCP Path Service
uucp-path 117 udp UUCP Path Service
nntp 119 tcp Network News Transfer Protocol [IESG] [IETF_Chair] 2018-07-06 [RFC3977]
nntp 119 udp Network News Transfer Protocol [IESG] [IETF_Chair] 2018-07-06 [RFC3977]
locus-con 127 tcp Locus PC-Interface Conn Server [Eric_Peterson] [Eric_Peterson]
locus-con 127 udp Locus PC-Interface Conn Server [Eric_Peterson] [Eric_Peterson]
netbios-ns 137 tcp NETBIOS Name Service
netbios-ns 137 udp NETBIOS Name Service
iso-ip 147 tcp ISO-IP [Marshall_Rose] [Marshall_Rose]
iso-ip 147 udp ISO-IP [Marshall_Rose] [Marshall_Rose]
knet-cmp 157 tcp KNET/VM Command/Message Protocol [Gary_S_Malkin] [Gary_S_Malkin]
knet-cmp 157 udp KNET/VM Command/Message Protocol [Gary_S_Malkin] [Gary_S_Malkin]
namp 167 tcp NAMP [Marty_Schoffstahl] [Marty_Schoffstahl]
namp 167 udp NAMP [Marty_Schoffstahl] [Marty_Schoffstahl]
print-srv 170 tcp Network PostScript [Brian_Reid] [Brian_Reid]
print-srv 170 udp Network PostScript [Brian_Reid] [Brian_Reid]
multiplex 171 tcp Network Innovations Multiplex
multiplex 171 udp Network Innovations Multiplex
cl-1 172 tcp Network Innovations CL/1

IANA assigned this well-formed service name as a replacement for "cl/1".
[Kevin_DeVault] [Kevin_DeVault]
cl/1 172 tcp Network Innovations CL/1 [Kevin_DeVault] [Kevin_DeVault] This entry is an alias to "cl-1". This entry is now historic, not usable for use with many common service discovery mechanisms.
cl-1 172 udp Network Innovations CL/1

IANA assigned this well-formed service name as a replacement for "cl/1".
[Kevin_DeVault] [Kevin_DeVault]
cl/1 172 udp Network Innovations CL/1 [Kevin_DeVault] [Kevin_DeVault] This entry is an alias to "cl-1". This entry is now historic, not usable for use with many common service discovery mechanisms.
xyplex-mux 173 tcp Xyplex [Bob_Stewart] [Bob_Stewart]
xyplex-mux 173 udp Xyplex [Bob_Stewart] [Bob_Stewart]
mailq 174 tcp MAILQ [Rayan_Zachariassen] [Rayan_Zachariassen]
mailq 174 udp MAILQ [Rayan_Zachariassen] [Rayan_Zachariassen]
vmnet 175 tcp VMNET [Christopher_Tengi] [Christopher_Tengi]
vmnet 175 udp VMNET [Christopher_Tengi] [Christopher_Tengi]
genrad-mux 176 tcp GENRAD-MUX [Ron_Thornton] [Ron_Thornton]
genrad-mux 176 udp GENRAD-MUX [Ron_Thornton] [Ron_Thornton]
xdmcp 177 tcp X Display Manager Control Protocol [Robert_W_Scheifler] [Robert_W_Scheifler]
xdmcp 177 udp X Display Manager Control Protocol [Robert_W_Scheifler] [Robert_W_Scheifler]
nextstep 178 tcp NextStep Window Server [Leo_Hourvitz] [Leo_Hourvitz]
nextstep 178 udp NextStep Window Server [Leo_Hourvitz] [Leo_Hourvitz]
bgp 179 tcp Border Gateway Protocol [Kirk_Lougheed] [Kirk_Lougheed]
bgp 179 udp Border Gateway Protocol [Kirk_Lougheed] [Kirk_Lougheed]
bgp 179 sctp BGP [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260]
aci 187 tcp Application Communication Interface [Rick_Carlos] [Rick_Carlos]
aci 187 udp Application Communication Interface [Rick_Carlos] [Rick_Carlos]
dls 197 tcp Directory Location Service
dls 197 udp Directory Location Service
at-7 207 tcp AppleTalk Unused
at-7 207 udp AppleTalk Unused
dbase 217 tcp dBASE Unix [Don_Gibson] [Don_Gibson]
dbase 217 udp dBASE Unix [Don_Gibson] [Don_Gibson]
dsp3270 246 tcp Display Systems Protocol [Weldon_J_Showalter] [Weldon_J_Showalter]
dsp3270 246 udp Display Systems Protocol [Weldon_J_Showalter] [Weldon_J_Showalter]
subntbcst-tftp 247 tcp SUBNTBCST_TFTP

IANA assigned this well-formed service name as a replacement for "subntbcst_tftp".
[John_Fake] [John_Fake]
subntbcst_tftp 247 tcp SUBNTBCST_TFTP [John_Fake] [John_Fake] This entry is an alias to "subntbcst-tftp". This entry is now historic, not usable for use with many common service discovery mechanisms.
subntbcst-tftp 247 udp SUBNTBCST_TFTP

IANA assigned this well-formed service name as a replacement for "subntbcst_tftp".
[John_Fake] [John_Fake]
subntbcst_tftp 247 udp SUBNTBCST_TFTP [John_Fake] [John_Fake] This entry is an alias to "subntbcst-tftp". This entry is now historic, not usable for use with many common service discovery mechanisms.
set 257 tcp Secure Electronic Transaction [Donald_Eastlake] [Donald_Eastlake]
set 257 udp Secure Electronic Transaction [Donald_Eastlake] [Donald_Eastlake]
td-service 267 tcp Tobit David Service Layer
td-service 267 udp Tobit David Service Layer
270 tcp Reserved

Contact Information

ID Name Organization Contact URI Last Updated
[Bill_Croft] Bill Croft mailto:Croft&sumex-aim.stanford.edu
[Bob_Braden] Bob Braden mailto:Braden&isi.edu
[Bob_Stewart] Bob Stewart mailto:STEWART&xyplex.com
[Brian_Reid] Brian Reid mailto:reid&decwrl.dec.com
[Christopher_Leong] Christopher Leong mailto:leong&kolmod.mlo.dec.com
[Christopher_Tengi] Christopher Tengi mailto:tengi&princeton.edu
[David_Zimmerman] David Zimmerman mailto:dpz&rutgers.edu
[Don_Gibson] Don Gibson mailto:sequent!aero!twinsun!ashtate.A-T.COM!dong&uunet.UU.NET
[Donald_Eastlake] Donald Eastlake mailto:d3e3e3&gmail.com
[Eric_Peterson] Eric Peterson mailto:lcc.eric&seas.ucla.edu
[Gary_S_Malkin] Gary S. Malkin mailto:GMALKIN&xylogics.com
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[John_Fake] John Fake mailto:fake&us.ibm.com
[Jon_Postel] Jon Postel mailto:postel&isi.edu
[Kevin_DeVault] Kevin DeVault
[Kirk_Lougheed] Kirk Lougheed mailto:LOUGHEED&mathom.cisco.com
[Leo_Hourvitz] Leo Hourvitz mailto:leo&next.com
[Mark_McCahill] Mark McCahill mailto:mpm&boombox.micro.umn.edu
[Marshall_Rose] Marshall Rose mailto:mrose17&gmail.com 2024-07-29
[Marty_Schoffstahl] Marty Schoffstahl mailto:schoff&nisc.nyser.net
[Maurice_R_Turcotte] Maurice R. Turcotte mailto:mailrus!uflorida!rm1!dnmrt%25rmatl@uunet.uu.net
[Randall_Stewart] Randall Stewart IETF TSVWG mailto:rrs&lakerest.net
[Rayan_Zachariassen] Rayan Zachariassen mailto:rayan&ai.toronto.edu
[Rick_Carlos] Rick Carlos mailto:rick&ticipa.csc.ti.com
[Robert_Thomas] Robert Thomas mailto:BThomas&f.bbn.com
[Robert_Ullmann] Robert Ullmann mailto:ariel&world.std.com
[Robert_W_Scheifler] Robert W. Scheifler mailto:RWS&xx.lcs.mit.edu
[Ron_Thornton] Ron Thornton mailto:thornton&aerostation.org 2020-09-01
[Weldon_J_Showalter] Weldon J. Showalter mailto:Gamma&mintaka.dca.mil